SOPC Builder - Unable to generate simulation models

I'm using Quartus II 10.1 Subscription Edition on Windows 7. I'm trying to generate an SOPC system with simulation models, but it's giving me errors when attempting to generate sim models for various VIP IP blocks.

Info: Error: Top-level design entity "alt_tpg" is undefined

Info: Error: Quartus II Analysis & Synthesis was unsuccessful. 1 error, 0 warnings

Info: Error: Peak virtual memory: 287 megabytes

Info: Error: Processing ended: Tue Dec 14 22:55:07 2010

Info: Error: Elapsed time: 00:00:02

Info: Error: Total CPU time (on all processors): 00:00:02

Error: Unable to generate simulation model for alt_tpg

It generates sim models for the Clocked Video Output and DDR2 modules, though. Anyone have any ideas?